The present invention relates to fiber optic links for connecting, for example, the central processing unit (CPU) of a computer to peripheral equipment such as monitors, printers, modems and the like. More particularly, it relates to a fiber optic connector assembly including mateable plug and receptacle connectors having cooperative mating structures which ensure accurate coaxial alignment of optical fiber ends in an optical cable with opto-electronic devices (OEDs) associated with an electrical component. In a preferred embodiment, a connector arrangement exhibiting exceptional electromagnetic interference (EMI) shielding is provided.
Fiber optic technology is increasingly used both in conjunction with and in place of conventional electrical circuits and components for a variety of different functions. In particular, it is especially desired in the field of data transmission to substitute fiber optic technology for more conventional copper technology, whenever possible. One reason for this is that fiber optic connections per se are generally less sensitive to EMI effects and exhibit reduced EMI emissions, as compared with their conventional counterparts. As a consequence, fiber optic transmission lines generally do not have to be as rigorously shielded against EMI. Another major reason is that fiber optic systems are able to handle more data, transmitted at higher data rates than copper-based components.
Different known fiber optic connectors are used for interconnecting fiber optic cables and for interconnecting OEDs to fiber optic cables. Examples of fiber optic connectors are disclosed in U.S. Pat. Nos. 4,167,303 issued Sept. 11, 1979 to Bowen et al., 4,534,616 issued Aug. 13, 1985 to Bowen et al., and 4,547,039 issued Oct. 15, 1985 to Caron et al. and Japan Patent 58-58510 published Apr. 7, 1983. Disadvantages of the known fiber optic connectors are their complexity and the resulting difficult and painstaking assembly required.
For example, each of the above-identified patents describes a fiber optic plug and receptacle connector system requiring a multitude of additional parts, other than the plug connector per se and the receptacle connector housing, to ensure proper positioning and alignment of the optical fiber end to the lens of the OED. These additional parts require considerable assembly steps, increase inventory requirements and add to the cost of the connectors.
Another major disadvantage of the above-cited connectors is that they do not provide an adequately shielded receptacle arrangement for modern computer link applications. Generally, the CPU of a computer generates relatively large amounts of EMI emissions. CPUs are generally shielded in accordance with FCC regulations to reduce EMI emissions emanating from a CPU from entering the environment in an effort to reduce EMI effects from interfering with telecommunications signals used by the general public. In many modern computer applications, the security of the computerized information is important. For these applications, preventing EMI emissions from escaping from a CPU is especially desired because these EMI emissions may be picked up by nearby receivers. The received emissions may be used by unauthorized persons to reconstruct the computer intelligence signals which generated the EMI emissions.
In accordance with modern applications, the fiber optic cable link may be used to connect the CPU of a computer to peripheral equipment. Generally, a metallic cabinet or housing connected to ground surrounds the internal components of a CPU to provide a shielded enclosure. Input/output (I/O) ports including receptacle connectors mounted in a housing panel must now be similarly shielded to maintain the shielded enclosure and protect the environment from undesirable effects of EMI escaping through the I/O ports. The above-cited patents do not describe or suggest the provision of adequate shielding for these applications.
Recently, there has been a dramatic expansion in the computer peripherals market, not only in terms of the types of peripheral devices available, but also in terms of their capabilities. For example, CRT monitors are available in color as well as monochrome, and may be of a high resolution or standard resolution type. Printers are available which can receive one or more character formats and/or are capable of printing at differing printer head rates. Various equipment including monitors and printers, as well as modems are now available which are capable of operating under one or more data transmission rates or baud rates.
CPUs are now capable of transmitting output data signals appropriate to each type and grade of peripheral equipment and most have multiple capabilities. It is desirable to be able to use the same I/O port of a computer to connect these varying types of peripheral equipment to the CPU. In this context, it is especially desired to provide a shielded switch integral to the connector arrangement capable of expressing at least one piece of binary information to the CPU to identify the type of peripheral equipment being linked with it, e.g., a color monitor vs a monochrome monitor, or a high resolution vs a standard resolution monitor, and so on. The provision of such a switch may permit the CPU to internally format the output to an appropriate form for that particularly identified peripheral equipment.